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No. 6|8,|37. Patented Jan. 24, I899.

C. E. SCRIBNER.

SIGNAL FOR TELEPHONE SWITCHBOARDS.

(Application filed Dec. 8, 1896.)

(No Model.)

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NITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE \VESTERN ELECTRIC COMPANY, OF SAME PLACE.

SIGNAL FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 618,137, dated January 24, 1899.

Application filed December 8,1896. Serial No- 614,875. (No model.)

To a. whom, it may concern: other relay interposed seriallyin the conduc- Be it known that 1, CHARLES E. SCRIBNER, tor of the plug-circuit, a supervisory signal a citizen of the United States, residing at Chicontrolled by that relay, (being lighted when cago, in the county of Cook and State of Illithe relay is inert,) and a normally open local 55 nois, have invented a certain new and usecircuit containinga winding of this latter reful Improvement in Signals for Telephonelay, togetherwith sWitch-contacts,whichclose Switchboards, (Case No.435,) of which the folthe break in the circuit when the relay is exlowing is a full, clear, concise, and exact decited. Other switch-contacts also are proscription, reference being had to the accompavided upon the relay arranged to short-cir- 6o [0 nying drawing, forming a part of this specificuit the winding thereof, which is interposed cation. in the telephonic circuit during the excite- My invention pertains to signals for telement of the local winding of the relay, so phone-lines in telephone-switchboards dethat its resistance is removed from the telesigned to respond automatically to currents phonic circuit. The current through the 65 in the line determined by the condition of local circuit of the relay is controlled by suitthe station apparatus of use or disuse, and able switch-contacts, which are open when thus to inform the operator continuously of the corresponding plug is returned to its norsuch condition. mal condition of disuse. This special appa- It concerns particularly the supervisory ratus may be associated with the Well-known 70 2o signals, which are commonly associated with form of switchboard in which a relay permaconnecting-plugs provided for uniting lines nently connected with the line controls a loin the switchboard and are intended to indical circuit, including a subsidiary line-signal, cate to the operator the subscribers response together with a resistance-coil, and having at the called substation and the discontinuconnections terminating in special contact- 75 ance of conversation. pieces of the spring-jacks of the line by which I have aimed to provide two signals having, the subsidiary line-signal becomes shunted respectively, the significations mentioned and when a plug is inserted into a spring-jack. to so organize the system that these signals In adapting the appliances of the plug-circuit shall be displayed only at the proper times, and supervisory apparatus of the present in- 80 and thus shall have positive and definite vention to the line apparatusof suchaswitchmeanings. board I choose to effect this shunting of the Afurther feature of theinvention consists subsidiary line-signal to efface this signal in a novel device for causing the efi'acement displayed as an initial call-signal through the of the initial call-signal in the act of making agency of a conductor including a resistance- 85 3 5 connection with the line in response thereto. coil and leading from the battery which ex- It is usual in systems furnished with sigcites that signal and terminatingin acontactnals designed for automatic operation to conpiece of the answering-plug which registers struct and arrange the appliances at the stawith the before-mentioned special contacts of tion, so that the removal of the telephone the spring-jack of the calling-line. In the 0 40 from its switch for use shall close a normally case of the answering-line, or that line which open circuit, and thus permit a current to is called for, I attain the same resultshuntflow in the line-circuit from a central source ing the line-signal--by means of a lamp of current, which excites a relay and debrought into parallel or shunt of the subsiditermines the display of a subsidiary line-sigary signal, but controlled, as before stated, 95 nal. The present invention is adapted for by means of the relay in the plug-circuit in use in connection with appliances of this deconjunction with the line-relay. In the opscription. Itconsistsin the combination,with eration of this new system the removal of the the usual plug-circuit, of a relay in a branch station-telephone for use causes the display therefrom, together with a source of current, oft-he subsidiary line-signal, after which the no a local circuit including a subsidiary clearresponse to the signal on the part of the oping-out signal controlled by the relay, anerator by inserting a plug into the springall jack efIaces this signal. The establishment of connection with the line called for causes the excitement of the supervisory signal, which remains excited until the called party has responded, but is hidden thereafter durin g the connection. The replacement of both station-telephones on their switches causes the display of the clearing-out signal.

The invention is shown in the attached drawing, which represents two substations connected by the usual line-circuits with signaling and switching appliances in a switchboard.

The telephones, bell, and telephone-switch at the substation are arranged, as before mentioned, to close the line-circuit through a path of comparatively low resistance during the use of the telephones, the circuit being open as to continuous current at other times, although it should permit the transmission of alternating calling-currents to operate the bell.

The line conductors l and 2 from the substation are led to aspring-jack CL in the switchboard. Thence they are extended through the windings of a relay 1) to the poles of a battery c, which is common to the different lines of the exchange. The armature-lever of this relay is connected to earth through a conductor 3, which includes a resistance-coil d, and is also connected by a conductor 4 with special contact-pieces e in the spring-jacks of the line. The contact-anvil of the relay forms the terminal of a wire 5, which is connected with the free pole of a grounded battery f and which includes a subsidiary line-signal (a small incandescent lamp,) associated with the spring-jack a in the switchboard.

The usual plugs 72. and h are provided in the switchboards, their like line-contacts being connected together through conductors 6 and 7 which constitute the plug-circuit. A calling-key '1} and a listening-key kare furnished in connection with each plug-circuit. A wire 8 extends from conductor 6 of the plugcircuit to one pole of the battery 0 and another wire 9 extends from conductor 7 to the otherpole of the same battery. Each of these wires includes a winding of the magnet of a relay Z. The conductors are, in effect, a bridge of the plug-circuit, including the source of current 0, together with these windings of the relay. The relay should have suflicient impedance to prevent the shunting of telephonic current from the plug-circuit through this path. The switch-contacts of this relay control the clearing-out signal through the medium of local-circuit connections, which will be described presently. A winding on the magnet 0' of another relay 0 is interposed in the conductor 7 of the plug-circuit between the plug 7?. and the point of connection with the circuit of conductor 9.

r The plugs 71. and 72/ have in addition to their usual line-contact other contact-pieces p, which are arranged to register with the thimbles e of spring-jacks, into which they are inserted. The contact 1) of plug 72. forms the terminal of a wire 10, which leads to the free pole of the grounded battery f. It is interrupted,however,at switch-contacts controlled by the relay l. One portion of the conductor is connected with the lever of the relay. A branch from the other portion extends to the forward contact-anvil of the relay, including a resistance coil, and a parallel branch from the same portion extends to the back contact of the relay and includes the clearing-out signal-lamp q. The contactpiece 19 of plug 77, likewise forms the terminal of a wire 11, leading to the same pole of the battery f. This wire includes a supervisorysignal lamp T, which is associated with plug h in the switchboard, being, if desired, located near the normal resting-place of the plug. About this lamp is a shunt-circuit 12, which includes an auxiliary winding 0 of the relay 0, together with a pair of switch-contacts 0 and 0*, controlled by that relay, arranged to be closed when the relay becomes excited. The armature-lever of the relay closes also other contact-pieces o and 0 which ordinarily create a break in a shuntcircuit 13 about the winding 0' of the relay.

The operation of these dilt'erent devices in the process of establishin gconnection between the two telephone-lines may now be traced. The removal of the receiving-telephone from its switch-hook at one of the substationssay at station A-permits the battery 0 to create in that line a current which excites the relay 1) and causes the display of the linesignal g in the switchboard. In response to this signal the attendant inserts an answering-plug h into the spring-jack a of the line, and at the same time brings her telephone into connection with the pl ug-circuit 6 7, and

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thus into communication with the calling subscriber by means of listening-key 7c. The insertion of plug it into the spring-jack brought the conductor 10 into parallel with the signal-lamp g, the two thus in multiple connection being in series in a circuit containing the battery f and the resistance-coil d. Under this condition the current divided between the two lamps would be insufficient to light either. It will be observed, however, that since the line-circuit at the substation was already closed for the use of the telephone in giving the order when the plug h was inserted into the spring-jack a current was produced from battery 0 through the windings of relay Z, whereby the latter was excited and caused to close the conductor 10 through the resistance-coil, leaving the clearing-outlamp on open circuit. Thus in the act of making connection with the line the line-signal became extinguished, while the clearingout signal (1 remained unlighted. Having received from the subscriber the order for the required connection,the operatorinserts plug h into the spring-jack a of the line to station B and operates the calling-key v to ring the bell at that station. The act of inserting this plug into the springj ack brought conductor 11 into parallel with conductor 4, as in the case of the calling-line; but since the relay Z) of the called line is not excited and the circuit through the line-lamp g of that line is not complete current from battery f will flow through conductors 11, and 3 sufficient to light the lamp 7'. This lamp will remain in this condition until the subscriber at the called substation responds to the call and removes his telephone from the switch for use. Then since the line-circuit will become closed through a path of low resistance at the substation current from battery 0 will flow through the windings of relay l and through cond uctor 7 of the plug-circuit, including the winding 0' of relay 0 to the substation, returning through the other line conductor to battery 0. The current through winding 0 excites that relay and causes its armature to close both pairs of switch-contacts o o and o o. The closing of the former pair of contactpoints completes the shunt 12 about the supervisory lamp 0, and thus brings about the extinction of this lamp. The current through this shunt excites the relay through the agency of auxiliary winding 0 whereby the relay is put into aself-sustaining condition, which permits it to remain closed thereafter independently of current in the line-circuit. The closure of contact-points o o" short-circuits the winding 0 of the relay in the plugcircuit, and thus eliminates its resistance and impedance from the circuit. The linelamp of the answering subscriber does not become illuminated, since it is at all times shunted by the conductor 11. The line-circuits and apparatus have now reached a condition which is maintained during the continuance of conversation. If the calling subscriber at station A should replace his telephone on its switch, the relay 1) of that line would become inert and would interrupt the circuit through the corresponding line-signal; but since the relay [would still be excited by current flowing out to the station E the clearing-out signal q would not be illuminated. If subscriber at station B should replace his telephone on its switch, the telephone at station A being still in position for use the supervisory signal '1" would not become lighted, since it would still be shunted by the closed circuit 12. At the termination of conversation the subscribers at both stations replace their telephones on their switches, and thus interrupt the line-circuits. The supervisory signal 0' remains still shunted by circuit 12, and hence does not become lighted. Current through relay Z is now interrupted, however, so that this relay becomes inert and permits its armature to close the branch of conductor 10, including the clearing-out lamp q. The line-relay l) of the calling-line having become inert, the circuit through line -lamp g is broken. Hence a sufficient currentis created by battery f in conductors 10 and 4 to light the clearing-out lamp. The illumination of this lamp constitutes an instruction to the operator to remove the connection between the lines. Thus the mechanism of this invention imparts a definite significance to each of the signal-lamps g and 0'. The former is ney er displayed excepting to call for a disconnection, while the latter is never displayed excepting when indicating that a called subscriber has not yet responded to the signal. The continued display of signal 7 demands another call to the substation or informs the operator that no response can be expected and that connection can be removed.

I claim as my invention and desire to secure by Letters Patent- 1. The combination with a telephone-line and means for producing current in the line while the telephone is in use, ofa relay-magnet in the line, a local circuit includinga supervisory signal, a normally open shunt about the signal controlled by the contact-points of the said relay, and a magnet-winding of the relay included in the shunt, substantially as described.

2. The combination with a telephone-line and means for producing current in the line in the use of the telephone, of a relay normally in the path of current in the line, a circuit and source of current therein, and switchcontacts for closing the circuit in making connection with the line, said circuit being controlled at a different point by switch-contacts of the said relay, a supervisory signal controlled by the relay and circuit connections of the said circuit including a winding of the relay completed in the closure of said circuit by the relay, whereby the condition of the supervisory signal remains unchanged after the initial response of the relay during connection with the line, as described.

3. The combination with a telephone-line and means for producing current therein, a spring-jack for the line and a plug and plugcircuit connected with the spring-jack, of a relay in the plug-circuit responsive to currents in the line, a normally open local circuit and switch-contacts of the plug and spring-jack adapted to put said circuit in operative condition during connection with the line, a supervisory signal in the local circuit and circuit connections of the relay with said local circuit controlling the current in the supervisory signal, and a winding of the relay associated with switch-contacts thereof adapted to bring the said winding into the local circuit in the response of the relay, as described.

4. The combination with a telephone-line and an extension therefrom through a springjack, plug and plug-circuit, a source of current connected with the plug-circuit, and means for closing the line at the station during the use of the telephone, of a relay having its magnet included in the plug-circuit, a local circuit closed in registering contactpieces of the plug and spring-jack and including a supervisory signal associated with IIO the plug, a shunt of the supervisory signal, and a winding of the relay included in said shunt, the continuity of said shunt being controlled by switch-contacts of the relay closed when it is excited, substantially as described.

5. The combination with a telephone-line and means for producing current therein while the telephone is in use, of a relay having one winding interposed in the telephonecircuit, a supervisory signal controlled by the relay, a local circuit and an auxiliary winding of the relay included in said circuit together with a source of current, said local circuit being controlled by switch-contacts of the relay to be closed when the relay is excited, a normally broken shortcircuit of said firstmentioned winding, and other switch-contacts of the relay closed when the relay is excited to complete said short circuit; whereby the supervisory signal is effaced and the winding of the relay interposed in the telephone-line is short-circuited when the telephone is brought into use, as described.

6. The combination with telephone-lines provided with switches adapted to close the lines during the use of the telephones and united through spring-jacks,plugs and a plugcircuit, of a source of current connected in a branch from the plug-circuit, an electromagnet iii-said branch controlling a clearing-out signal, being adapted to display the signal when the magnet is inert, a relay-magnet interposed in the line-circuit to the called station,and a supervisory signal controlled thereby, a local circuit including a winding of the said magnet and normally broken at two points, switch-contacts closed by the relay to complete one of said breaks, and registering switch-contacts in the plug and spring jack completing the other of said breaks, whereby the supervisory signal is made indicative of the disuse of both telephones while the supervisory signal is adapted to signalize the use of the telephone at the called station, as described.

7. The combination with a telephone-line and means for producing current in the line during the use of the telephone, a line-relay responsive to currents in the line, a local circuit controlled thereby, and a subsidiary signal in said local circuit, of an extension from the line through a spring-jack, plug and plugcircuit, a magnet having a winding interposed in the plug-circuit, a conductor closed through registering contact pieces of the spring-jack and plug in shunt of the said subsidiary line signal, a supervisory signal included in the said conductor, and a shunt about the supervisory signal controlled by the said magnet in the plug-circuit, substantially as described.

8. The combination with a telephone-line, means for producing current in the line during the use of the telephone, a relay connected with the line responsive to current therein, and aspring-jack and plug for makin g connection with the line, of a local circuit including a source of current and a resistance-coil divided into two parallel branches, one of said branches being controlled by the line-relay and including a secondary signal, and the other of the branches being closed in registering contacts of the spring-jack and plug, a supervisory signal and a resistancecoil, and a relay adapted to interpose the supervisory signal or the resistance-coil alternately into the second-mentioned branch, as described.

9. The combination with a telephone-line, a source of current in the line, a switch at the substation for closing the circuit in the use of the line, and a plug and spring-jack forming a part of the circuit of the line, of a relay in the line and a signal controlled thereby, circuit connections controlled by the said relay adapted to remove the resistance of the relay from the line when the relay is excited, other local-circuit connections including a winding of the relay, and switch-contacts of the relay adapted to close the said local circuit at one point controlled by the relay, to be closed when the relay is excited, and other switch-contacts controlling the said local circuit closed in registering contacts of the plug and spring-jack, substantially as described.

In witness whereof I hereunto subscribe my name this 5th day of November, A. D. 1896.

CHARLES E. SCRIBNER.

Vitnesses:

ELLA EDLER, DUNCAN E. WILLETT. 

